WASHINGTON – Bernie Sanders has acknowledged that Donald Trump managed to become US president by tapping into the anti-establishment anger of “a declining middle class” but said he will continue to challenge him.

“Donald Trump tapped into the anger of a declining middle class that is sick and tired of establishment economics, establishment politics and the establishment media.”

As thousands of demonstrators took to the streets of at least 16 US cities to protest against the election of Donald Trump, Sanders said he was prepared to work with the president-elect to help working families.

Sanders, the senator from Vermont, reluctantly backed Clinton in her bid for the presidency after a hard-fought Democratic campaign in which the two repeatedly clashed as he portrayed her as a member of a discredited elite, Guardian reported.

The statement said: “Donald Trump tapped into the anger of a declining middle class that is sick and tired of establishment economics, establishment politics and the establishment media.”

Sanders added: “People are tired of working longer hours for lower wages, of seeing decent paying jobs go to China and other low-wage countries, of billionaires not paying any federal income taxes and of not being able to afford a college education for their kids – all while the rich become very much richer.”

It concluded: “To the degree that Mr Trump is serious about pursuing policies that improve the lives of working families in this country, I and other progressives are prepared to work with him.

“To the degree that he pursues racist, sexist, xenophobic and anti-environment policies, we will vigorously oppose him.”

Meanwhile, violence has broken out at anti-Trump rallies across America overnight as tens of thousands marched against the President-elect before angry mobs attacked police, started fires and shut down highways.

Thousands of demonstrators took to the streets of at least 16 US cities to protest against the election of Donald Trump. Many shouted the slogan “Not my president”. Others burned orange-haired effigies of the businessman, the BBC reported.